).I was reminded of this whole sruthi discussion and Arvindh when I was reading up about Gowlipantu, of all things. There it categorically states "....The slightly sharpened Sudha madhyam (27/20) is a characteristic feature of this raga..." ( http://www.indiamusicinfo.com/raga/g.htm ).
On the one hand, Arvindh's measurements show that the CM sruthi ratios are really not needed to bring out the raga bhava, all one needs is the different gamakas. If I remember right, no one could provide an example of a straight execution of a note satisfying the sruthi ratios ( without much oscillatory gamaka ). This is further complicated by the fact that there is a wide variation on swarasthana frequencies by leading musicians without really affecting the ragas. And these variations are wider than the microtonal sruthi intervals.
On the other hand, we have descriptions like the above ( e.g. gowlipantu ) which are specific and categorical, and are defined as part of the raga lakshana.
Where does this leave us?